Why are so many Americans out of calorie balance and, thus, overweight? Many people believe that eating behaviors and physical activity behaviors (the two scales in the calorie balance diagram) are choices that people consciously make to satisfy their desires/cravings or to achieve their goals. And that people are out of calorie balance because they eat too much food and do too little physical activity. Seems relatively simple, right?

Maybe not. More and more public health practitioners are starting to realize that certain environmental cues are significant contributors to calorie imbalances. In a recent article published in the International Journal of Obesity1, researchers describe an "environmental tsunami of cues and stimuli that artificially make people hungry and lead them to unintentionally overconsume and remain excessively sedentary." They argue that excess eating and reduced physical activity may not be a conscious choice, but instead the result of "automatic and uncontrollable responses" to these environmental cues.

What are some of these environmental cues and the proposed mechanisms that cause automatic and unconscious eating? Here are some examples:

Mechanism: The brain secretes dopamine in response to food and images of food. Dopamine creates cravings and motivations to act – a response that is not controllable. Thus, food and food images (advertising) artificially stimulate people to feel hungry and overconsume.

Mechanism: The brain's mirror neurons are the mechanism through which people automatically respond to environmental stimuli, and mimic other individuals. In a study referenced in the International Journal of Obesity article, children were observed eating when they were served an excessively larger portion of food. When their plates had more food, the children automatically opened their mouths wider to accommodate more. Thus, there is evidence that motor activity begins prior to conscious awareness of that activity and we can't help but eat more when we are served more.

What do you think? Are eating and physical activity conscious or unconscious choices that we make? What can individuals do to avoid unhealthy environmental cues?

1Cohen, D.A. (2008).Obesity and the built enviornment; changes in enviornmental cues cause energy imbalances. International Journal of Obesity. 32, S137-S142.